Weinberg was born in Hanover, Germany, and resided there the first ten years of his life. As Jews in Nazi Germany, he and his family suffered increasing persecution. They emigrated in 1938, first to the United Kingdom and then in 1941 to New York State. Weinberg became a U.S. citizen, served in the U.S. Army during its Occupation of Japan in 1946-1947, and returned to receive a B.A. in social studies from the State University of New York at Albany. He received his MA (1949) and PhD (1951) in history from the University of Chicago.[1] Weinberg recounts some of his childhood memories and experiences in a two-hour long oral history interview for the United States Holocaust Memorial Museum.[2]

Weinberg has studied the foreign policy of National Socialist Germany and the Second World War for his entire professional life. His doctoral dissertation (1951), directed by Hans Rothfels, was "German Relations with Russia, 1939-1941," subsequently published in 1954 as Germany and the Soviet Union, 1939-1941. From 1951 to 1954 Weinberg was a Research Analyst for the War Documentation Project at Columbia University and was Director of the American Historical Association Project for Microfilming Captured German Documents in 1956-1957. After joining the project to microfilm captured records at Alexandria, Virginia, in the 1950s, Weinberg published the Guide to Captured German Documents (1952).[3] In 1958, Weinberg made the notable discovery of Hitler's so-called Zweites Buch (Second Book), an unpublished sequel to Mein Kampf, among captured German files. His find led to his publication in 1961 of Hitlers zweites Buch: Ein Dokument aus dem Jahr 1928, later published in English as Hitler's Second Book: The Unpublished Sequel to Mein Kampf (2003).

In 1953-1954, Weinberg was involved in a major scholarly debate with Hans-Günther Seraphim and Andreas Hillgruber on the pages of the Vierteljahrshefte für Zeitgeschichte journal over the question of whether Operation Barbarossa, the German invasion of the Soviet Union in 1941 was a preventive war forced on Hitler by fears of an imminent Soviet attack. Seraphim and Hillgruber argued for the preventive war thesis, which Weinberg stoutly opposed. Rothfels, editor of the Vierteljahrshefte für Zeitgeschichte, was annoyed by Hillgruber’s and Seraphim’s arguments and invited Weinberg to write a reply to their article. Weinberg argued that the German invasion was primarily prompted by Nazi racial theories concerning the necessity of winning Lebensraum at the expense of Russia together with Hitler’s ideological animosity towards what Hitler often called the “Judeo-Bolshevik” regime in the Soviet Union, and that the evidence for Soviet plans for an invasion of Germany in 1941 was slight. In the opinion of most historians, Weinberg effectively demolished Hillgruber’s and Seraphim’s case[citation needed]. This marked the beginning of the first of many clashes between Weinberg and Hillgruber over interpretations of German foreign policy, though it should be noted that in regard to the intentionalist-functionalist and globalist-continentalist debates (see below), the views of Weinberg and Hillgruber were quite similar. In a 1956 review of Hillgruber’s book Hitler, König Carol und Marschall Antonescu, Weinberg accused Hillgruber of engaging at times in a pro-German apologia such as asserting that World War II began with the Anglo-French declarations of war against Germany on September 3, 1939, rather than the German invasion of Poland on September 1, 1939.[4] In his 1980 monograph The Foreign Policy of Hitler's Germany Starting World War II 1937-1939, Weinberg noted that about the question of the war's origins that "my view is somewhat different" from Hillgruber's.[5] In his 1981 book World in the Balance, Weinberg stated that "Hillgruber's interpretation is not, however, followed here".[6] In his 1994 book A World At Arms, Weinberg called Hillgruber's thesis presented in his book Zweierlei Untergang - Die Zerschlagung des Deutschen Reiches und das Ende des europäischen Judentums (Two Kinds of Ruin The Smashing of the German Reich and the End of European Jewry) "...a preposterous reversal of the realities".[7] Weinberg sarcastically commented that if the German Army had held out longer against the Red Army in 1945 as Hillgruber had wished, the result would not have been the saving of more German lives as Hillgruber had claimed, but rather an American atomic bombing of Germany.[7]

Another major scholarly debate involving Weinberg occurred in 1962-1963 when Weinberg wrote a review of David Hoggan’s 1961 book Der erzwungene Krieg for the American Historical Review, which claimed that the outbreak of war in 1939 had been due to an Anglo-Polish conspiracy against Germany. Weinberg wrote a hostile review generally considered quite devastating, in which Weinberg suggested Hoggan had probably engaged in forging documents (the charge was later confirmed). Weinberg noted that Hoggan’s method comprised taking of all Hitler’s “peace speeches” at face value, and simply ignored evidence in favor of German intentions for aggression such as the Hossbach Memorandum.[8] Moreover, Weinberg noted that Hoggan often rearranged events in a chronology designed to support his thesis such placing the Polish rejection of the German demand for the return of the Free City of Danzig (modern Gdańsk, Poland) to the Reich in October 1938 in 1939, thereby giving a false impression that the Polish refusal to consider changing the status of Danzig was due to British pressure.[9] Finally, Weinberg noted that Hoggan had appeared to engage in forgery by manufacturing documents and attributing statements that were not found in documents in the archives.[10] As an example, Weinberg noted during a meeting between Neville Chamberlain and Adam von Trott zu Solz in June 1939, Hoggan had Chamberlain saying that the British guarantee of Polish independence given on March 31, 1939 “did not please him personally at all. He thereby gave the impression that Halifax was solely responsible for British policy”.[11] As Weinberg noted, what Chamberlain actually said was:

Subsequently both Hoggan and his mentor Harry Elmer Barnes wrote a series of letters to the American Historical Review protesting Weinberg’s review and attempting to rebut his arguments. Weinberg in turn published letters rebutting Barnes's and Hoggan’s claims.

Weinberg's early masterpiece was the two-volume history of Hitler's diplomatic preparations for war: The Foreign Policy of Hitler's Germany (1970 and 1980; republished 1994). In this work, Weinberg portrayed a Hitler committed to his ideology, no matter how inane or stupid it might seem to others, and therefore as a leader determined to use foreign policy to effect a specific set of goals. Weinberg thus countered others, such as British historian A.J.P. Taylor, who had argued in The Origins of the Second World War (1962) that Hitler had acted like a traditional statesman in taking advantage of the weaknesses of foreign rivals. The first volume of The Foreign Policy of Hitler's Germany received the George Louis Beer Prize of the American Historical Association in 1971.

Weinberg's attention then turned to the Second World War. He published dozens of articles on the war and volumes of collected essays such as World in the Balance: Behind the Scenes of World War II (1981). All such work was preparation for the release in 1994 of his 1000-page one-volume history of the Second World War, A World at Arms: A Global History of World War II. Weinberg continued his studies of the World War II era even after the publication of his general history by examining the conceptions of World War II's leaders about the world they thought they were fighting to create. It was published in 2005 as Visions of Victory: The Hopes of Eight World War II Leaders. In this book, Weinberg looked at what eight leaders were hoping to see after the war ended. The eight leaders profiled were Adolf Hitler, Benito Mussolini, General Hideki Tōjō, Chiang Kai-shek, Joseph Stalin, Winston Churchill, General Charles de Gaulle, and Franklin D. Roosevelt.

Weinberg has continued to be a harsh critic of those who claim that Operation Barbarossa was a "preventive war" forced on Hitler. In a very hostile review of Ernst Topitsch's book Stalin's War, Weinberg called those who promote the preventive war thesis as believers in "fairy tales".[12] In 1996, Weinberg was somewhat less harsh than in his review of Topitsch's book, but still very critical in his assessment of the Czech historian R.C. Raack's book Stalin's Drive to the West (which did not accept the preventive war thesis, but argued that Soviet foreign policy was far more aggressive than many other historians would accept, and Western leaders too pliant in their dealings with Stalin).[13]

In the globalist versus continentalist debate, concerning whether Hitler had ambitions to conquer the entire world or merely the continent of Europe, Weinberg takes a globalist view, arguing Hitler had plans for world conquest. On the question of whether Hitler intended to murder Europe's Jews before coming to power, Weinberg takes an intentionalist position, arguing that Hitler had formulated ideas for the Holocaust by the time he wrote Mein Kampf. In a 1994 article, Weinberg strongly criticized the American functionalist historian Christopher Browning for arguing that the decision to launch the “Final Solution to the Jewish Question” was taken in September–October 1941.[14] In Weinberg’s view, July 1941 was the more probable date[14] In the same article Weinberg praised the work of the American historian Henry Friedlander for arguing that the origins of the Holocaust can be traced to the Action T4 program, which began in January 1939[15] Finally, Weinberg strongly praised the thesis put forward by the American historian Richard Breitman that planning for the Shoah began during the winter of 1940-41, but argued that Breitman missed what Weinberg argued was a crucial point, that because the T4 program had generated public protests, the Einsatzgruppen massacres of Jews in the Soviet Union were intended as a sort of “trial run” to gauge reaction of the German people to genocide.[16]

A major theme of Weinberg’s work about the origins of the Second World War has been a revised picture of Neville Chamberlain and the Munich Agreement. Based on his study of German documents, Weinberg established that the demands Hitler had made concerning the cession of the Sudetenland region of Czechoslovakia were not intended to be accepted, but were rather to provide a pretext for aggression against the latter state.[17] Weinberg has established that Hitler regarded the Munich Agreement as a diplomatic defeat that deprived Germany of the war that was intended to be begin on October 1, 1938.[18] Weinberg has argued against the thesis that Chamberlain was responsible for the failure of the proposed putsch in Germany in 1938.[19] Weinberg has argued that the three visits to London in the summer of 1938 of three messengers from the opposition, each bearing the same message that if only Britain would promise to go to war if Czechoslovakia was attacked, then a putsch would remove the Nazi regime, each ignorant of the other messengers' existence, presented a picture of a group of people apparently not very well organized, and that it is unreasonable for historians to have expected Chamberlain to stake all upon the uncorroborated words of such a badly organized group.[19] In a 2007 review of Ian Kershaw's book Fateful Choices, Weinberg, though generally favorable to Kershaw, commented that Chamberlain played a far more important role in the decision to fight on despite the great German victories in the spring of 1940 and in ensuring that Churchill was his successor instead of the peace-minded Lord Halifax, than Kershaw gave him credit for.[20] Weinberg’s picture of Chamberlain has led to criticism; the American historian Williamson Murray condemned Weinberg for his “…attempts to present the British Prime Minister in as favorable a light as possible”.[21]

Squeezing the visit into just a few hours so as not to miss any of his teaching assignments at Chapel Hill, Weinberg reported in Newsweek that "on balance I am inclined to consider the material authentic."[this quote needs a citation] But Weinberg also noted that the purported journals would likely add less to our understanding of the Second World War than many might have thought and that more work would be needed to "make the verdict [of authenticity] airtight."[this quote needs a citation] When that work was undertaken by the German Federal Archives, the "diaries" were deemed forgeries. As evidence emerged that the diaries were forgeries, Weinberg modified his perception of them.

Weinberg supervised over two dozen Ph.D. dissertations during his career, along with many more M.A. theses. In 2003, thirteen of his former doctoral students presented him with a Festschrift honoring his contributions to the study of history and to their lives (The Impact of Nazism: New Perspectives on the Third Reich and Its Legacy).[citation needed] Weinberg was elected president of the German Studies Association in 1996.

In June 2009, Weinberg was selected to receive the $100,000 Pritzker Military Library Literature Award for lifetime excellence in military writing, sponsored by the Chicago-based Tawani Foundation.[22] As part of his acceptance, he gave a webcast lecture at the library on "New Boundaries for the World: The Postwar Visions of Eight World War II Leaders."[23]

^On the history of the captured German archives and Weinberg's role see Astrid M. Eckert, The Struggle for the Files. The Western Allies and the Return of German archives after the Second World War. Cambridge University Press 2012. ISBN 978-0-521-88018-3, 343-357.

^Weinberg, Gerhard Review of Stalin's War: A Radical New Theory of the Origins of the Second World War by Ernst Topitsch pages 800-801 from The American Historical Review, Volume 94, Issue # 3, June 1989 page 800

^Weinberg, Gerhard Review of Stalin's Drive to the West: The Origins of the Cold War by R.C. Raack pages 278-279 from Central European History, Volume 29, Issue #2, 1996

The Partisan Movement in the Yelnya-Dorogobuzh Area of Smolensk Oblast, Maxwell Air Force Base, Alabama: Air Research and Development Command, Human Resources Research Institute Headquarters, United States Air Force, 1954.

"The May Crisis, 1938" pages 213-225 from The Journal of Modern History Volume 29, Issue # 3 September 1957.

Review of The Reichswehr and the German Republic, 1919-1926 by Harold J. Gordon pages 414-415 from The American Historical Review, Volume 63, Issue # 2, January 1958.

Review of Documents on German Foreign Policy 1918-1945 pages 63–64 from The Journal of Modern History, Volume 31, Issue # 1, March 1959.

Supplement to the Guide to Captured German Documents. Washington D.C.: National Archives and Records Service, General Services Administration, 1959.

Review of Correspondence between the Chairman of the Council of Ministers of the U.S.S.R. and the Presidents of the U.S.A. and the Prime Ministers of Great Britain during the Great Patriotic War of 1941-1945 pages 142-143 from The Journal of Modern History, Volume 31, Issue # 2, June 1959.

Review of Hitler and Russia: The Third Reich in a Two-Front War, 1937-1943 by Trumball Higgins page 965 from The American Historical Review, Volume 72, Issue # 3 April 1967.

Review of While Berlin Burns: The Diary of Hans-Georg von Studnitz, 1943-1945 by Hans-Georg von Studnitz pages 208-209 from The Journal of Modern History, Volume 39, Issue # 2, June 1967.

Review of Germany: A Brief History by Walter Michael Simon page 413 from The Journal of Modern History, Volume 40, Issue # 3, September 1968

Review of The Trial of the Germans: An Account of the Twenty-two Defendants before the International Military Tribunal at Nuremberg by Eugene Davidson pages 670-671 from The Journal of Modern History, Volume 40, Issue # 4, December 1968.

Review of Stalin, Hitler, and Europe Volume I: The Origins of World War II, 1933-1939 by James E. McSherry page 660 from Slavic Review, Volume 27, Issue # 4, December 1968.

Review of Stauffenberg. The Architect of the Famous July 20th Conspiracy to Assassinate Hitler by Joachim Kramarz pages 669-670 from The Journal of Modern History, Volume 40, Issue # 4 December 1968.

Review of The Conspiracy Against Hitler in the Twilight War by Harold C. Deutsch pages 1027-1029 from The American Historical Review, Volume 74, Issue # 3, February 1969.

Review of The Rise of Fascism by Francis L. Carsten pages 122-123 from Political Science Quarterly, Volume 84, Issue # 1, March 1969.

"The Defeat of Germany in 1918 and the European Balance of Power, pages 248-260 from Central European History, Volume 2, Issue 3, September 1969.

Review of The Free City: Danzig and German Foreign Policy, 1919-1934 by Christoph M. Kimmich pages 168-169 from The American Historical Review, Volume 75, Issue # 1 October 1969.

Reviews of Republic to Reich: The Making of the Nazi Revolution edited by Hajo Holborn; Hitler's Weltanschauung: A Blueprint for Power by Eberhard Jäckel & Hitler: The Man and the Military Leader by Percy Ernst Schramm pages 306-307 from The American Political Science Review, Volume 68, Issue # 1, March 1974.

Reviews of The War Hitler Won: The Fall of Poland, September 1939 by Nicholas Bethell& Codeword Barbarossa by Barton Whaley pages 361-362 from Slavic Review, Volume 33, Issue # 2, June 1974.

Reviews of The Swiss Corridor: Espionage Networks in Switzerland during World War II by Jozef Garlinski & The Hut Six Story: Breaking the Enigma Codes by Gordon Welchman pages 91–92 from Military Affairs, Volume 47, Issue # 2, April 1983.

Review of Germany and the Far Eastern Crisis, 1931-1938: A Study in Diplomacy and Ideology by John P. Fox page 421 from The American Historical Review, Volume 88, Issue # 2, April 1983.

Reviews of Poland's Place in Europe: General Sikorski and the Origin of the Oder-Neisse Line, 1939-1943 by Sarah Meiklejohn Terry & The Civilian Population and the Warsaw Uprising of 1944 by Joanna K. M. Hanson pages 566-568 from The Journal of Modern History, Volume 56, Issue # 3, September 1984.

Review of Germany, Russia, and the Balkans Prelude to the Nazi-Soviet Non-Aggression Pact by Marilyn Giroux Hitchens pages 711-712 from The Journal of Modern History, Volume 56, Issue # 4 December 1984.

Review of German Resistance to Hitler by Peter Hoffmann pages 1419-1420 from The American Historical Review, Volume 94, Issue # 5, December 1989.

Review of Between Churchill and Stalin: The Soviet Union, Great Britain, and the Origins of the Grand Alliance by Steven Merritt Miner pages 1168-1169 from The American Historical Review, Volume 95, Issue # 4, October 1990.

Reviews of Paths to War: New Essays on the Origins of the Second World War edited by Robert Boyce & Esmonde M. Robertson & How War Came: The Immediate Origins of the Second World War, 1938-1939 by Donald C. Watt pages 382-385 from The Journal of Modern History, Volume 64, Issue # 2, June 1992

“Some Thoughts on World War II” pages 659-668 from The Journal of Military History, Volume 56, Issue # 4, October 1992.

Review of The Opening of the Second World War by David Wingate Pike page 341 from The Journal of Military History, Volume 57, Issue # 2, April 1993.

Co-written with Edwin Bridges, Gregory Hunter, Page Putnam Miller, David Thelen “Historians and Archivists: A Rationale for Cooperation” pages 179-186 from The Journal of American History, Volume 80, Issue # 1, June 1993.

“Comments on the Papers by Friedlander, Breitman, and Browning” pages 509-512 from German Studies Review, Volume 17, Issue # 3, October 1994.

Review of The German Resistance against Hitler: The Search for Allies Abroad, 1938-1945 by Klemens von Klemperer pages 222-223 from The Journal of Modern History, Volume 67, Issue # 1 March 1995

Review of Explaining Auschwitz and Hiroshima: History Writing and the Second World War, 1945-1990 by Richard J. B. Bosworth pages 553-554 from The Journal of Military History, Volume 59, Issue # 3, July 1995.

Review of The Origins of Nazi Genocide: From Euthanasia to the Final Solution by Henry Friedlander pages 176-179 from German Studies Review, Volume 19, Issue # 1 February 1996.

Review of Stalin's Drive to the West: The Origins of the Cold War by R.C. Raack pages 278-279 from Central European History, Volume 29, Issue #2, 1996.

“Changes in the Place of Women in the Historical Profession: A Personal Perspective” pages 323-327 from The History Teacher, Volume 29, Issue # 3, May 1996.

Review of Why the Allies Won by Richard Overy pages 573-574 from The Historical Journal, Volume 39, Issue # 2, June 1996.

“Germany’s War for World Conquest and the Extermination of the Jews” pages 119-133 from Holocaust and Genocide Studies, Volume 10, 1996.

Review of Cooperation under Fire: Anglo-German Restraint during World War II by Jeffrey W. Legro page 1212 from The American Historical Review, Volume 101, Issue # 4, October 1996.

Review of Ambassador Frederic Sackett and the Collapse of the Weimar Republic, 1930- 1933: The United States and Hitler's Rise to Power by Bernard V. Burke pages 1027-1028 from The Journal of Modern History, Volume 68, Issue # 4, December 1996.

Review of The Holocaust and Strategic Bombing: Genocide and Total War in the Twentieth Century by Eric Markusen & David Kopf pages 89–90 from The American Historical Review, Volume 102, Issue #1, February 1997

“World War II Scholarship, Now and in the Future” pages 335-345 from The Journal of Military History, Volume 61, Issue # 2, April 1997.

Review of From Peace to War: Germany, Soviet Russia, and the World, 1939-1941 by Bernd Wegner pages 834-835 from The Journal of Military History, Volume 61, Issue # 4, October 1997.

Review of The Germanic Isle: Nazi Perceptions of Britain by Gerwin Strobl pages 820-821 from The Journal of Military History, Volume 65, Issue # 3, July 2001.

Review of From Versailles to Pearl Harbor: The Origins of the Second World War in Europe and Asia by Margaret Lamb & Nicholas Tarling page 600 from The Journal of Military History, Volume 66, Issue # 2, April 2002.